ttd

It’s been a good long while since I’ve really dissected a bit of electronics. But I finally got another chance after uncovering an old broken CD/radio/cassette player in the basement! After some tests, I determined that the CD player part of it didn’t work. Since no one uses archaic cassette tapes anymore, and a radio that weighs ten pounds is pretty impractical, I naturally snapped it up to tear it apart. 🙂

The boombox before dissection; note that it’s quite dusty. It was manufactured in 1997 so it was about 20 years old.

Disassembling it was pretty trivial. There was only a few screws which held the casing together, and each internal part also held in place with screws. The most challenging part was removing the large speakers. Each was both glued and screwed, so it took a little extra prying to get them off.

The boombox can be powered from both batteries and the house current, so there’s both a transformer and a large compartment to hold eight D cells. There’s one large PCB that combines the circuits for the CD player, cassette player, and radio player, with a few offshoot PCBs to connect the controls.

Finally I have a rather ambitious Tech Tear Down: an entire computer desktop case! It was sitting in the basement waiting to be disposed of, so naturally I decided to take it apart. The computer is a Dell Inspiron that runs Windows 7. I’m not sure why it was junked; I think there was some kind hardware problem. Because it has so many components inside, I’m dividing this TTD into a bunch of parts. First off is the CD-ROM drive!

The computer actually had two different CD- ROM drives. One of them was just a readable CD-ROM drive, and the other one was read/writeable, allowing you to burn CDs. Since both drives were still in working condition within the computer, I took apart the readable drive, and kept the read/write one to save in case I need to replace one in the future or maybe even build my own computer (or add it to my RasPi)!

The CD-ROM drives, each a metal rectangular box, had their own cubby in the computer case. They’re connected to the motherboard by just a ribbon cable. In the above picture, you can see the space in the case that they took up.

It was easy to take apart. The first thing to do was remove the metal casing on the back with a screwdriver. The rest of the components inside were either snapped or screwed in place, so it was just a matter of making good use of my screwdriver. The ‘motherboard’ PCB was right on top, with assorted ribbon cables connecting to the laser and the three motors. One motor ejects and closes the CD holder in a system of slides and gears, one spins the CD inside for the laser to read, and one moves the laser up and down using a screw mechanism.

Because I didn’t break or damage anything, I could theoretically put the whole disk drive back together again, but I don’t think that’ll happen. I found one of my mom’s long lost classical music CDs that was left in one of the drives. Luckily I like take stuff apart otherwise she would have lost it permanently! 🙂

Time for an insides look at two old video game controllers: one from the Playstation 2 (2000), and one from the Sega Genesis System (early 1990s). The PS2 controller was not in working condition, so I completely teared it down, while the Sega Genesis controller still worked so I had to be more careful with it.

Because the two controllers were made about a decade apart, the Sega Genesis controller is extremely simple compared to the PS2 one. After removing the screws on the back, all there was inside was a PCB with capacitive buttons and one IC. Because the controller is completely digital (unlike the PS2), there’s really no need for the controller to have any other elements.

The PS2 controller was an entirely different story. It was jam packed with all sorts of stuff. First of all, the PS2 controller has analog joysticks that take up quite a bit of space up on the inside. There’s one PCB, to which a rectangular LED is soldered as well as multiple ICs. The PS2 controller also has a vibration affect, created by two DC motors with off-centered weights attached to them. Like the Sega Genesis Controller, the PS2 controller has digital capacitive buttons. What was interesting was how the little iconic x-o-square-triangle buttons popped out. I might be able to integrate them into a future electronics project!

I found an old Philips TV remote and of course took it apart. Inside there was just a PCB underneath the rubber button mass. Each button is actually a capacitive sensor. When the rubber bottom of each button comes into contact with the cap, it changes the amount of capacitance. This signal from the remote is transmitted via an infrared LED that the TV picks up and decodes. The picture below shows the LED on the top of the PCB. It’s labeled IED1.

This is one of my strangest Tech Tear Downs yet… My dad, my brother, and I cleaned up our backyard, filling up a Bagster all the way to the top. We went through an old junk pile, and buried underneath everything and covered up with leaves and dirt was the electronic guts of an old electronic organ that we trashed sometime around 2007. I was of course extremely curious, and despite the dirt, I salvaged the bulk of the electronics to see what they we’re made of or course to see if there was anything useful.

Basically, there was four large PCBs stacked and bolted on top of each other. They consisted of diodes, transistors, resistors, and capacitors, as well as a few op amp ICs. Other than on the top layer, there was little corrosion on the components, and I wondered as to how useful they would be, considering that they’re from the 80s and they’ve been subject to very extreme temperatures, as well as water.

I was excited to see that there was loads and loads of diodes (the image above shows a section of one PCB after I removed a bunch of the diodes; they were easy to get to). I would estimate there was close to 80 silicon diodes that I could have used in a breadboard. I set a table and got out all my tools and spent a while removing the diodes and a few of the resistors, using mainly a small flat-head screw driver and needle-nosed pliers. I was able to get maybe 50 diodes, a few resistors, and a few transistors, as well as a few useless souvenir ICs.

I tested a few of the diodes out, and they worked great. The transistors were junk, and most of the resistors had leads that were too short. But now I have enough diodes to make a decimal-to-binary converter!

Above is where I was working.

There’s a few differences I noted between these four giant PCBs and modern day ones. First, the etched copper connections were very curvy, instead of rectangular and crammed together as you see on modern machine-made PCBs. Secondly, the wires coming off the PCBs weren’t directly soldered onto the board. Instead, a little metal spike pokes out of the board and the wire wraps tightly around the spike, so the joint is more mechanical, as you can see in the picture below.

Quite frankly, I don’t really know how these PCBs work inside the organ. They were labeled in a few spots as having something to do with ‘rhythm’ and there was a large mass of wires exiting the PCBs, so my guess is these boards were responsible for generating the different tones on the organ.

I had the sudden urge the other day to tear apart another electronic device, the victim being the computer mouse that I use for my Raspberry Pi that happened to being lying so very innocently on my desk. The picture above is an ‘artsy’ flash shot of the inside of the mouse.

Taking it apart was easy. There was only one screw in the center of the undersided that I removed with my trusty old mini Phillips screwdriver. The bottom and the top plastic pieces easily came apart, revealing a PCB pressed into the bottom, connected to the wire coming out of the mouse. The PCB itself wasn’t attached with glue or screws, so it popped out easily.

You can see the little red left and right click buttons in the image below. When you click the mouse, the plastic of the shell of the mouse hits the read button. It’s not plastic that makes the clicking noise when it hits the button, its the button itself that makes the noise. The scroll wheel has a third little red button under it that allows for the scroll wheel to click. In the middle, there’s a motion sensor that detects where the mouse is moving. Inside the black box on the right is a red LED, the ‘laser’ that lights up the bottom when the mouse is on. In addition there’s a multitude of caps and resistors.

In the images below, you can see the bottom of the PCB, and how it fits into the plastic casing. There’s a little transparent piece of plastic that goes under the PCB, and it helps focus the LED light.

WARNING: DO NOT ATTEMPT TO DISASSEMBLE OR TAMPER WITH YOUR LAPTOP COMPUTER CHARGER; they contain giant capacitors which are capable of delivering fatal electric shocks if tampered with or touched. The charger used for this Tech Tear Down had not been plugged into a wall for over a year, and the capacitors were completely discharged.

Ever wonder what’s inside that little black box on your computer charger? Recieving yet more throw away electronics, I took apart an old computer charger to see what was inside.

Before I delve into what was inside, here’s a little background on what the little black box does. When you plug something into a wall, you’re plugging into your house voltage, which is usually around 120 volts, with alternating current (AC). That many volts is enough to fry most electronics, so there has to be a way to reduce the voltage and the current down to something more usable. That’s the job of the little black box on your laptop charger. It takes the 120 volts and steps it down to a much lower voltage, usually between 10-20 volts. You may notice a your charger getting hot if you have it plugged in for a while; that’s the extra voltage getting dissapated as heat.

It took quite a while to get it open, as it should, to keep the components inside from getting damaged or more importantly, touched. This first image is what it looked like with the black casing off. The printed circuit board and all of its components are encased in a few layers in metal and plastic to help dissapate the heat.

With the casing off, most of the guts were exposed. There’s great gobs of white glue, and a significant amount yellow plastic tape. In the middle you can see a capacitor (it has a smaller piece of yellow tape on it), or a component that holds and stores and electric charge. This would be just one of the caps (short for capacitor) responsible for zapping you should you open the charger up without discharging the unit first.

Next I painstakingly removed all the tape and began to tear it apart to see all the components. It’s mainly made up of large capacitors and inductors (components that hold a current).

I completely destroyed it, saving the ‘cool’ components. I got a nice 300Ω resistor (I didn’t have any of them), a giant 420 V 120 uF cap (good as a souvenir), some useless caps, and a decent small inductor I’ll try out on something. If you look at the tan PC board below, you can see that it’s well labeled as to where the components go, and every part has a name, like C1 or CX1.

Overall, it was interesting to take apart a computer charger. I saw some capacitor varieties I’ve never seen before.